1. Field of the Invention
The invention relates to a method and composition for the prevention and treatment of mastitis in animals.
2. Description of the Prior Art
Mastitis is an inflammation of the mammary gland which occurs in animals in response to an injury therein. The disease is estimated to cost the United States economy approximately $2 billion per year. In dairy animals, mastitis usually occurs when bacteria invade the teat canal and mammary glands. These bacteria multiply and produce toxins (pyrogens) that cause injury to the milk secreting tissue and ducts throughout the mammary gland. In addition bacteria cause degradation of milk quality. This bacterial infection initiates an inflammatory response by the animal, stimulating the production of mediators of inflammation. Polymorphonuclear neutrophil (PMN) leukocytes, monocytes and other immune cells move to the site of infection, and masses of immune cells may pass between milk producing cells into the lumen of the alveoli, increasing the somatic cell counts (SCC) and further damaging secretory cells and milk quality (Virginia Cooperative Extension. 2011. Understanding the Basics of Mastitis. 404-233). Clots may form by aggregation of leukocytes and blood clotting factors and may block the ducts and prevent complete milk removal, resulting in scar formation and permanent loss of function of that portion of the mammary gland [Zhan and Khan. 2006. Pakistan Vet. J. 26(4):204-208].
Mastitis also causes significant changes to the milk from infected animals. The level of casein, the major milk protein of high nutritional quality, declines, while the level of lower quality whey proteins increases. An increase in SCC is also observed, and serum albumin, immunoglobulins, transferrin and other serum proteins pass into the milk. Other changes include increased conductivity, increased sodium and chloride concentrations, and decreased potassium and calcium concentrations (Virginia Cooperative Extension. ibid; Zhan and Khan. ibid).
The most common mastitis pathogens are found either in the udder (contagious pathogens) or the animal's surroundings (environmental pathogens), such as bedding, manure, soil, etc. Contagious mastitis pathogens (Staphylococcus aureus, Streptococcus agalactiae) are spread from infected udders to “clean” udders during the milking process through contaminated teatcup liners, milkers' hands, paper or cloth towels used to wash or dry more than one cow, and possibly by flies. Although new infections by environmental pathogens (other streptococci such as Streptococcus uberis and Streptococcus dysgalactiae and coliforms such as Escherichia coli and Klebsiella pneuomoniae) can occur during milking, primary exposure appears to be between milkings. Coliform infections are usually associated with an unsanitary environment (manure and/or dirty, wet conditions), while Klebsiella are found in sawdust that contains bark or soil. Approximately 70-80% of coliform infections become clinical (abnormal milk, udder swelling, or systemic symptoms that include swollen quarters, watery milk, high fever, depressed appetite or elevated body temperature). Environmental pathogens are often responsible for most of the clinical cases. About 50% of environmental streptococci infections display clinical symptoms (Virginia Cooperative Extension. ibid).
Conventional techniques for prevention of mastitis generally emphasize limiting exposure of the teats to potential pathogens by proper sanitation and minimizing access to contaminated environments such as mud, manure and stagnant water, teat dipping after milking, and culling of chronically infected animals. Antibiotic therapy is also utilized for animals at drying off (i.e., between lactation cycles). The current state-of-the-art treatment for mastitis in infected animals is antibiotic therapy (Virginia Cooperative Extension. ibid; Zhan and Khan. ibid). However, the use of antibiotics for treatment of milk-producing animals is a concern for many consumers and food safety advocates.